The interaction of fl bacteriophage specific proteins with the cytoplasmic membrane of Escherichia coli is being investigated. Attempts are being made to isolate chemical amounts of the products of phage genes IV, VI, VII, IX and X. These proteins will be characterized by two-dimensional gel electrophoresis, amino acid analysis and amino and carboxyl end-group analysis and the results compared with amino acid sequence predicted by the phage DNA sequence. We will try to obtain antibodies to these proteins to use as probes to investigate the nature of the synthesis and possible interaction of these proteins with the bacterial membrane.